Document Python connector extras and optional dependency compatibility

[Whxuan0701]

Summary

Add a single Python contributor/user reference mapping Semantic Kernel connectors to their install extras and important optional dependency constraints.

Current implementation facts

Semantic Kernel's Python package supports multiple connectors with optional third-party SDKs. Import-time failures can otherwise surface far from installation.

Problem

Users and contributors must inspect pyproject metadata and individual connector docs to determine which extra installs a connector and which upstream versions are supported.

Scope

• Add a generated or maintained compatibility table.
• Include connector name, import path, install extra, and upstream package.
• Link to connector-specific configuration docs.
• State how version constraints are validated in CI.

Non-goals

• Do not broaden dependency version ranges.
• Do not combine all connectors into the default install.

Acceptance criteria

• Every public Python connector maps to an extra or explicitly states none.
• Table entries can be checked against package metadata.
• Documentation builds successfully.

I searched Semantic Kernel issues and PRs for Python connector extras, optional dependencies, compatibility matrix, and install guidance before filing this proposal.